Imaging of chlorophyll-a-fluorescence in leaves: Topography of photosynthetic oscillations in leaves of Glechoma hederacea

Abstract

Images of chlorophyll-a-fluorescence oscillations were recorded using a camera-based fluorescence imaging system. Oscillations with frequencies around 1 per min were initiated by a transient decrease in light intensity during assimilation at an elevated CO2-concentration. The oscillation was inhomogenously distributed over the leaf. In cells adjacent to minor veins, frequency and damping rate was high, if there was any oscillation. In contrast, the amplitude was highest in cells most distant from phloem elements (maximal distance about 300 μm). The appearance of minor veins in oscillation images is explained by a gradient in the metabolic control in the mesophyll between minor veins and by transport of sugar from distant cells to phloem elements. The potential of fluorescence imaging to visualize 'microscopic' source-sink interactions and metabolic domains in the mesophyll is discussed.

Autotoxic effects of essential oils on photosynthesis in parsley, parsnip, and rough lemon

“…Images of chlorophyll fluorescence were captured by a video camera. The images provide quantitative spatially resolved data on the quantum efficiency of electron transport through photosystem II (φ PSII ) Genty et al, which, under low oxygen, is closely correlated with rates of CO 2 assimilation (DiMarco et al 1990;Edwards & Baker 1993;Siebke & Weis 1995).…”

Photosynthetic oscillation in individual cells of the marine diatom Coscinodiscus wailesii (Bacillariophyceae) revealed by microsensor measurements

“…However, the experimental designs with respect to the frequency of measurements may have not have been appropriate for detecting oscillations of the type detected here for oxygen evolution and pH using continuous recording procedures. The fluorescence technique has detected oscillations in the leaves of C 3 land plants (Siebke and Weis 1995;Ferimazova et al 2002).…”

Oscillations of the internal CO2 concentration in tobacco leaves transferred to low CO2

“…Such a feedback could result in oscillatory phenomena occurring in a leaf system. Oscillations in the Calvin cycle (usually having periods of minutes) have been reported for leaves exposed to high atmospheric CO 2 concentrations (Siebke and Weis, 1995) and are explained by the linkage of the Calvin cycle with phosphate turnover (Laisk and Walker, 1986;Igamberdiev et al, 2006) and with operation of other metabolic pathways, e.g., glycolysis (RydePettersson, 1991). Whether such oscillations also occur between photorespiratory CO 2 release (in the mitochondria) and photosynthetic CO 2 uptake (in the chloroplast) has not been investigated.…”